INTRODUCTION: The reorientation of the health care model in Brazil is based on a strategy to structure a primary care network to cover the health needs of the population through access to family health teams. The impact of primary care on the health of the population can be assessed by tracking hospital admissions due to conditions sensitive to ambulatory care, an initiative that has been developed in recent years in several countries and also in Brazil OBJECTIVE: To analyze hospital admission trends for some conditions sensitive to ambulatory care in the Association of Cities of the South End of Santa Catarina - AMESC, associating it to the quality of care offered by the Family Health Program-PSF METHOD: An exploratory research with characteristics of an ecological study that qualified the primary care offered, based on a questionnaire directed to PSF professionals and information collected through national data information, defining two population groups: one assisted by services with a basic standard and another one assisted by services below this standard. Hospital admissions for some selected causes of these two populations were compared in the 1999-2004 period, analyzing their trend and statistical association. RESULTS: The statistical analysis suggested that there was a trend toward the decline of admissions due to pneumonia in <5 y-o and >60 y-o in both the population with appropriate basic and non-appropriate ambulatory care. Diabetes mellitus hospitalizations tended to decline in the population with adjusted basic ambulatory care. Diarrhea rates tended to stabilize in both groups, but in the cities with appropriate care its magnitude was much smaller. Strokes increased in cities with appropriate care, with a smooth linear decrease for the population assisted in a non-appropriate way. For Acute Myocardial Infarction, for cities with appropriate care, as for the ones with non-appropriate care, the rates showed a trend toward increase, although a little smaller in the cities with appropriate PSF CONCLUSION: Some positive changes can be perceived in the development of admission rates due to ambulatory care-sensitive conditions, that can be associated with the higher coverage and the best care received from the PSF.